Metal Organometallic Chemistry

Keywords Bioorganometallic chemistry Medicinal organometallic chemistry Metal carbonyls Metallocenes N-heterocyclic carbenes Peptides Peptide Bioconjugates Peptide synthesis Solid phase synthesis Tris(pyrazolyl)borate ligands... 

Alloys Ammonia N-donor Ligands Hard Soft Acids and Bases Mercury Organometallic Chemistry Metal Ion Toxicity S-donor Ligands Semiconductor Interfaces Superconductivity Water 0-donor Ligands Zeolites. 

Chromium Organometallic Chemistry Metallic Materials Deposition Metal-organic Precursors. 

Tungsten tetrachloride is the most synthetically useful binary tungsten chloride after WCl and is an important precursor in coordination and organometallic chemistries, metal-metal bonded dimngsten chemistry, materials synthesis," hexatungsten chloride cluster synthesis, and catalysis. ... 

Whereas CP2MX2 compounds are ubiquitous ia early transition-metal organometallic chemistry, the thorium analogues are rather unstable. 

As a result of the systematic application of coordination-chemistry principles, dozens of previously unsuspected stnicture types have been synthesized in which polyhedral boranes or their anions can be considered to act as ligands which donate electron density to metal centres, thereby forming novel metallaboranc elusters, ". Some 40 metals have been found to act as acceptors in this way (see also p. 178). The ideas have been particularly helpful m emphasizing the close interconnection between several previously separated branches of chemistry, notably boron hydride clu.ster chemistry, metallaboranc and metallacarbaborane chemistry (pp. 189-95). organometallic chemistry and metal-metal cluster chemistry. All are now seen to be parts of a coherent whole. 

R. H. Crabtree The Organometallic Chemistry of the Transition Metals, Wiley, New York, 1988, 440 pp. 

The steady trend towards increasing stability of rather than M compounds in the sequence Ge, Sn, Pb is an example of the so-called inert-pair effect which is well established for the heavier post-transition metals. The discussion on p. 226 is relevant here. A notable exception is the organometallic chemistry of Sn and Pb which is almost entirely confined to the state... 

Indeed, it is the cyclopentadienyls which provide the major part of the organometallic chemistry of this group and they are known for metal oxidation states of IV, III and II though III... 

Also in the divalent state, Pd and Pt show the class-b characteristic of preferring CN and ligands with nitrogen or heavy donor atoms rather than oxygen or fluorine. Platinum(IV) by contrast is more nearly class-a in character and is frequently reduced to Pt by P- and Aj-donor ligands. The organometallic chemistry of these metals is rich and varied and that involving unsaturated hydrocarbons is the most familiar of its type. 

Organometallic chemistry (see p. 1199) is not particularly extensive even though gold alkyls were amongst the first organo-transition metal compounds to be prepared. Those of Au are the most stable in this group, while Cu and Ag (but not Au ) form complexes, of lower stability, with unsaturated hydrocarbons. 

Recenl work has defined more carefully ihe nature of active sites. Metal surfaces are thought to contain three main types of sites terraces, ledges (or steps) and kinks, which correspond to one, two. and three coordinatively unsaturated sites of organometallic chemistry. These sites display differing activities toward saturation, isomerization, and CKChiingQ 7 J0,68 JO 1.103,104,105). 

For a theoretical consideration of the metal-silicon interaction in silylene complexes, the fragment orbital description proves to be very useful [148], This approach has been extensively used in the organometallic chemistry of carbon and allows a basic understanding of the interrelations also by means of a qualitative description. 

Multiple bonds between transition metals and bare main group elements links between inorganic solid state chemistry and organometallic chemistry. W. A. Herrmann, Angew. Chem., Int. Ed. Engl., 1986, 25,56 (115). 

Although olefin metathesis had soon after its discovery attracted considerable interest in industrial chemistry, polymer chemistry and, due to the fact that transition metal carbene species are involved, organometallic chemistry, the reaction was hardly used in organic synthesis for many years. This situation changed when the first structurally defined and stable carbene complexes with high activity in olefin metathesis reactions were described in the late 1980s and early 1990s. A selection of precatalysts discovered in this period and representative applications are summarized in Table 1. 

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